| 1 | Synthesis, Crystal Structure and Calculated β Value of a Tetrahedral Zinc (II) Complex——Zn(2-NH_2py)_2Br_2显示文摘A new zinc(II) complex, Zn(2-NH2py)2Br2 (py=pyridine), has been synthesized, and its molecular structure has been confirmed by IR, elemental analysis and -ray crystal structure analysis. Its space group is P21/n with Mr=413.43 (C10H12Br2N4Zn), a=7.435(2), b=12.865(3), c=14.186(4)? b=94.08(2)? V=1353.5(5) 3, Z=4, Dc=2.029 g/cm3, F(000)=328, ?2.378mm-1, R=0.0283, wR=0.0501. The total observed reflections with I≥2?I) were 5314, of which the independent reflections were 3106. The complex structure contains a distorted tetrahedron formed by four atoms coordinated to zinc atom, namely two bromide atoms and two nitrogen atoms. The two ZnBr bond lengths within one molecule, 2.3763(6) and 2.4002(5)? respectively, are not equal; and so are the two ZnN bond lengths, which are 2.031(2) and 2.044(2)?respectively. The calculation results using PM3 method through MOPAC software package in Chem 3D show that its first molecular hyperpolarizability b value is 5.210-30esu, which is comparable with that of p-nitroaniline. No bulk SHG effect has been detected due to the centrosymmetric space group. | REN Peng a SU Nan-Bing a QIN Jin-Gui a Michael W. Day b CHEN Chuang-Tianc ( aDepartment of Chemistry, Wuhan University, Wuhan 43007, China) ( bBeckman Institute, California Institute of Technology, Pasadena, CA91125, USAQ ) ( cBeijing R & D Center | 2002 | Chinese Journal of Structural Chemistry2002，21，1： | 3 |
| 2 | 地球科学与社会:全球综述显示文摘如果人类要长期继续生存和繁荣,必需了解支持人类需求的地球和它的能力。地球科学的任务是认识地球,进行推断,从而达到规划人类社会的目的。推动地球活动的内因是其内部的对流作用,外因是太阳能,固体地球、水圈、大气圈与生物圈形成了全球循环系统。固体地球科学委员会注重的主要研究课题包括:1.地球内部动力学;2.岩石圈的形成和演化;3.大陆动力学;4.生物的多样性和灭绝;5.活动的行星:地质灾害;6.地质历史中的全球环境与变化;7.持续的能源与矿产资源;8.了解人类与地球的相互作用与运用这些知识于社会。人类社会是地球循环的一部分,它从地球中提取资源,把废料又送回地球内,它破坏地球的自然保护圈。对于全球的认识将可指导人类社会减少对地球的流体层与土壤这个保护圈的野蛮性破坏。因此,地球科学是社会的一个好的测试器。 | P.J.Wyllie(Division of Geological and Planetary Sciences,California Institute of Technology,Pasadena,CA 91125) | 1994 | 地学前缘1994，1，Z1： | 3 |
您所在的机构暂未开通此部分的功能，请联系管理员